As a robot hand having multiple joints like a human finger, there is known a robot hand that includes a base section corresponding to the back of a human hand, a first finger link corresponding to a proximal phalange of a finger, a second finger link corresponding to an intermediate phalange of a finger, and a third finger link corresponding to a distal phalange of a finger. The first finger link is pivotably connected to the base section. The second finger link is pivotably connected to the first finger link. The third finger link is pivotably connected to the second finger link.
When a robot hand grips an object, the object is wound by the finger. To wind the object with a finger, the first finger link, the second finger link and the third finger link are configured to be sequentially bent. As a typical robot hand, there is known a robot hand which is configured such that a second finger link is bent interlocking with a first finger link when the first finger link is bent, and a third finger link is bent interlocking with the second finger link when the second finger link is bent. A driving source for bending the finger is a motor or an actuator, such as a linear actuator. The driving source imparts driving force to the first finger link so that the first finger link is bent relative to the base section. When the first finger link is bent, the second finger link and the third finger link are sequentially bent.
A typical robot hand of conventional art is able to stably “grip” an object, however, suffers from a problem of difficulty in “manipulating” the object. To “grip” refers to that an object is firmly held, while to “manipulate” refers to that a machine, for example, is manipulated to bring it into action. For example, when a robot is assigned to a screw tightening job using an electric screwdriver, the robot hand is required to firmly hold (grip) the handle of the electric screwdriver and pull (manipulate) the trigger of the electric screwdriver. A typical robot hand of conventional art excels in firmly holding the handle of an electric screwdriver, however, suffers from a problem of not being good with pulling the trigger of the electric screwdriver.
As a robot hand that solves the problem, the applicant has proposed a robot hand having a finger in which a small actuator is incorporated into each joint of the finger (see Patent Literature 1). In this robot hand, a first actuator is incorporated into a first joint between a base section and a first finger link. A second actuator is incorporated into a second joint between the first finger link and a second finger link. A third actuator is incorporated into a third joint between the second finger link and a third finger link. The robot hand described in Patent Literature 1 is able to independently bend the first to third finger links, and hence is able to grip an object and manipulate the gripped object.